Portable communication device

ABSTRACT

A portable communication device for conference calls, comprising at least first and second speech encoder paths with first and second inputs ( 2   a,   2   b,   3 ) for connection to first and second recording devices ( 4,5 ), respectively, and at least one output ( 6,7 ) connected to signal processor means ( 8;8′ ) for receiving and processing first and second electronic signals from said recording devices ( 4,5 ) via said first and second speech encoder paths for transmission to a transmitter/receiver ( 10 ) operatively connected to said signal processor means ( 8,8′ ), wherein said apparatus is adapted to receive said first and second electronic signals simultaneously even if the signals are different, and said apparatus comprises a summator ( 8;27 ) adapted to sum said first and second electronic signals into a sum signal for transmission to said transmitter/receiver ( 10 ).

FIELD OF THE INVENTION

[0001] The present invention relates to a portable communication deviceand a method for conference calls, and more particularly to a portablecommunication device with conference call capability, wherein at leasttwo parties can use the same portable communication device forcommunicating with at least a third party in a conference call.

BACKGROUND OF THE INVENTION

[0002] A conventional mobile phone is used for a single user and,consequently, the mobile phone has a single microphone for receivingsound waves of human voice of the user of the phone and a singleloudspeaker for reproducing sound for the user.

[0003] However, in some situations it is desirable to set up a call withmore than two participants. Some prior art mobile phones, like theEricsson mobile phone T28 and others, solve this problem by providing aconference call service that enables calls involving more than twoparticipants. To create a conference call with three participants A, B,and C, A has a conventional prior art mobile phone with conference callcapability and B and C may have either conventional prior art mobilephones or just conventional telephone sets. A makes a call to B. When Banswers the call, A puts B on hold and makes a second call, this time toC. Then, A joins the calls through a particular function provided in thenetwork. Now, all participants can hear each other at the same time.

[0004] A conference call can be created in other ways than the exampledescribed above, but this is well known and therefore not describedherein in detail.

[0005] When for example A and B are at the same place and want to set upa conference call with C who is remote, it is inconvenient to create aconference call involving three phones as described above. Further, itseems to be unnecessarily expensive to have two ongoing calls at thesame time. A more common and less expensive way of setting up aconference call in this case is to use a system phone provided with anadditional fixed loudspeaker and fixed microphone. Then, A can make acall to C and instead of using the regular handset both A and B speakwith C through the additional microphone and listen to C via theadditional loudspeaker. Thus, only one call is charged at the same time.

[0006] However, it is not always possible to find a system phone in thevicinity. For example in an airport transit hall or another public placeyou are reduced to the case with two mobile phones, one for A and onefor B for creating a conference call with the third participant C.

SUMMARY OF THE INVENTION

[0007] The object of the present invention is to provide a portablecommunication device such as a mobile phone with an improved conferencecall capability, wherein at least two parties can use the same portablecommunication device for communicating with at least a third party in aconference call.

[0008] This is accomplished by a portable communication device accordingto the present invention, comprising at least first and second speechencoder paths with first and second inputs for connection to first andsecond microphones, respectively, and at least one output connected to asignal processor which receives and processes first and secondelectronic signals from the microphones via the first and second speechencoder paths for transmission to a radio frequency transmitter/receiveroperatively connected to the signal processor, wherein the apparatus isadapted to receive the first and second electronic signalssimultaneously even if the signals are different, and the apparatuscomprises a summator for summing the first and second electronic signalsinto a sum signal before transmission to the radio frequencytransmitter/receiver for further transmission.

[0009] A more specific object of the invention is to provide an improvedCODEC block for use in a portable communication device for conferencecalls.

[0010] This object is achieved by a CODEC block, comprising first andsecond speech encoder paths, with first and second inputs for connectionto first and second microphones, respectively, wherein the block isadapted to receive first and second electronic signals simultaneouslyfrom the microphones even if the signals are different, and the blockcomprises a summator for summing the first and second electronic signalsinto a sum signal before transmission to a radio frequencytransmitter/receiver of the phone.

[0011] An advantage of the present invention is that a conference callcan be created between three participants with only one ongoing call,wherein two of the participants use a common portable communicationdevice.

[0012] It should be emphasised that the term “comprises/comprising” whenused in this specification is taken to specify the presence of statedfeatures, integers, steps or components but does not preclude thepresence or addition of one or more other features, integers, steps,components or groups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] An illustrative embodiment of the invention will now be describedin conjunction with the accompanying drawings, in which

[0014]FIG. 1 is a block diagram of a portable communication device withconference call capability according to a first embodiment of theinvention; and

[0015]FIG. 2 is a block diagram of a portable communication device withconference call capability according to a second embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0016]FIG. 1 of the drawings shows a block diagram of a first embodimentof a portable communication device with conference call capabilityaccording to a first embodiment of the invention.

[0017] The term portable communication device, which herein after isreferred to as a mobile telephone apparatus, includes all equipment suchas mobile telephones, pagers, communicators, i.e. electronic organizers,smartphones, cordless phones, satellite phones or the like.

[0018] The mobile telephone apparatus comprises a CODEC (coder anddecoder) block 1 provided with first microphone/line inputs 2 a,2 badapted for a conventional fixed microphone 4 and a secondmicrophone/line input 3 adapted for example a handsfree microphone 5 ina portable handsfree device. The line inputs 2 a,2 b and/or 3 can beadapted for another kind of recording device such as a tape recorder orplay back device for music etc.

[0019] In a conventional mobile phone with a single speech encoder patha user can speak either in the fixed microphone 4 or, when the handsfreeunit is connected to the phone, in the handsfree microphone 5. Accordingto the invention the CODEC block 1 has two speech encoder paths, whichaccept analogue speech from either the fixed microphone 4 or thehandsfree microphone 5, separately or simultaneously. A first party Acan speak in the fixed microphone 4 and a second party B in thehandsfree microphone 5 at the same time, using the same mobile-phone forcommunicating with at least a third party C in a conference call, whichis described in further detail below. The term conference call includescommunication between users as well as apparatuses, such as voice mailetc, or a combination thereof.

[0020] In the case when the two speech encoder paths operatesimultaneously, they generate two different PCM output bit streams viafirst and second PCM outputs 6 and 7 for connection to a DSP (digitalsignal processor) 8. However, the PCM signals could be multiplexed onthe same physical output in an alternative embodiment of the invention.

[0021] The DSP 8 processes the PCM output bit streams or digital signalsfrom the speech encoder paths, wherein the DSP generates a sum signal ofthe two bit streams. A central processing unit (CPU) 9 is provided inthe phone for interpretation and execution of program instructions forcommunication with the DSP 8 and for controlling the operations of othercomponents and blocks in the phone. The CPU 9 receives a digital sumsignal processed by the DSP based on the PCM output bit streams fortransmission to a radio frequency transmitter/receiver 10. The radiofrequency transmitter 10 generates an RF signal for transmission throughan antenna 11 to a remote mobile phone, or to a conventional telephone,not shown in the drawings, via for example a base station in aconventional cellular network.

[0022] Further, the CODEC block 1 has a speech decoder path, whichoperates simultaneously and independently from the speech encoder pathsfor duplex operation. The decoder path accepts a PCM signal on its PCMinput 12 from the DSP 8 and generates analogue signals for output onfirst earphone/line outputs 13 a,13 b or a second earphone/line output14. The first earphone/line outputs 13 a,13 b are adapted for aconventional fixed earphone 15 and the second earphone/line output 14 isadapted for a handsfree earphone 16 of the portable handsfree device.Additionally, the line outputs 13 a,13 b and/or 14 can be adapted foranother kind of output device such as a recording device.

[0023] In a conventional mobile phone a user listens either in the fixedearphone 15 or, when the handsfree unit is connected to the phone, inthe handsfree earphone 16.

[0024] However, in the case described above, when the handsfree deviceis connected and the two speech encoder paths operate simultaneouslyaccording to the invention, the fixed earphone 15 and the handsfreeearphone 16 also operate simultaneously.

[0025] The user has to be provided with a sidetone from its microphoneto feel comfortable in the meaning of perceiving its own voice during atelephone conversation. Thus, the user of the fixed microphone 4 andearphone 15 receives a sidetone from the fixed microphone 4 and the userof the handsfree device receives a sidetone from the handsfreemicrophone 5. The sidetones are generated by the DSP 8 based on the twodifferent bit streams from the two speech encoder paths and are providedto the earphones 15 and 16 through the speech decoder path, undersupervision of the CPU 9. This means that each user (party A or B)receives also the other user's (party B or A) voice signals. Hence, atrue conference call capability with at least three participants isprovided by the mobile phone according to the invention.

[0026] Again referring to FIG. 1 and the CODEC block 1, there are twoalmost identical speech encoder paths. The first path comprisesmicrophone/line inputs 2 a,2 b adapted for the fixed microphone 4connected to a microphone amplifier 17, the output of which is connectedto a filter block 18. The filter block 18 comprises a transmitprogrammable gain stage (TX PGA) for adjustment of the total gain in theproduct for different sensitivities of the microphones, ananalogue-to-digital converter (ADC) and a transmit band pass filter,which converts the analogue signal from the microphone to a digitalsignal and filters the resulting signal before input to a PCM (PulseCode Modulation) encoder 19. The resulting PCM signal is transmitted tothe DSP 8 for signal processing including summing as described above.The second path differs from the first path in that its microphone/lineinput 3 is adapted for the handsfree microphone 5. The microphone signalis further supplied to a filter block 20, directly or via a preamplifier17′ if necessary. The filter block 20 comprises a transmit programmablegain stage (TX PGA), an analogue-to-digital converter (ADC), and atransmit band pass filter, which converts the analogue signal from thehandsfree microphone to a digital signal and filters the resultingsignal before input to a PCM (Pulse Code Modulation) encoder 21. Theresulting PCM signal is transmitted to the DSP 8 for signal processingand summing with the PCM signal from the first speech encoder path.

[0027] As described above the CODEC block 1 has a speech decoder path,which operates simultaneously and independently from the speech encoderpaths for duplex operation. The PCM signal accepted by the PCM input 12from the DSP 8 is transmitted to a PCM voice decoder 22. The outputsignal from the decoder 22 is fed through a programmable volume control23. Further, the volume-controlled signal is fed through a filter block24, comprising a receiver low-pass filter, a digital-to-analogueconverter for converting the PCM decoded signal into an analogue signal.Before input to a first earphone amplifier 25 for the fixed earphone 15and/or to a second earphone amplifier 26 for the handsfree earphone 16,the signal passes a receive programmable gain stage (PGA) in the filterblock 24, enabling adjustment of the circuit for different sensitivityof the earphone(s) and is spread in the path.

[0028] Generally, when the handsfree device 5,16 is connected to themobile phone, the profile or mode of the phone is set automatically to aportable handsfree profile. This profile implies at least that the fixedearphone and fixed microphone are disconnected. The conference callcapability according to the invention is, however, activated by changingto a particular pre-programmed profile in the phone or by changing acorresponding setting in the phone.

[0029] A second embodiment of a block diagram of a mobile telephoneapparatus with conference call capability according to the invention isshown in FIG. 2.

[0030] The difference between the first and second embodiment is thatthe summing is performed on the digital PCM signals in the firstembodiment and on the analogue signals in the second embodiment.

[0031] The first speech encoder path according to the second embodimentof the CODEC block 1′ comprises the microphone/line inputs 2 a,2 badapted for the fixed microphone 4 connected to a microphone amplifier17 in a similar way as for the first embodiment. However, the output ofthe amplifier 17 is connected to an analogue summator 27. The secondpath also has a microphone/line input 3, which is adapted for thehandsfree microphone 5. The microphone signal is further supplied to thesummator 27, directly or via a preamplifier 17′ if necessary.

[0032] The output of the amplifier comprises the analogue sum signal.The signal is filtered through a filter block 28, which comprises atransmit programmable gain stage (TX PGA), an analogue-to-digitalconverter (ADC), and a transmit band pass filter, which converts theanalogue signal from the microphone to a digital signal and filters theresulting signal before input to a PCM (Pulse Code Modulation) encoder29. The resulting PCM sum signal is transmitted to the DSP 8′ for signalprocessing before transmission through a remote party through the RFtransmitter 10.

[0033] As described above, each user has to be provided with a sidetonefrom its respective microphone to feel comfortable in the meaning ofperceiving its own voice during a telephone conversation. Thus, the userof the fixed microphone 4 and earphone 15 receives a sidetone from thefixed microphone 4 and the user of the handsfree device receives asidetone from the handsfree microphone 5, respectively. In the secondembodiment the sidetones are generated by a sidetone block connectedbetween the output of the filter block 28 in the speech encoder path andthe input of the filter block 24 in the speech decoder path, which iscontrolled by the CPU 9. Thus, the sidetones are based on the twodifferent analogue signals from the microphone 4 and the handsfreemicrophone 5 and are provided to both earphone 15 and the handsfreeearphone 16, respectively. This means that each user (party A or B)receives even the other user's (party B or C) voice signals. Hence, atrue conference call capability with at least three parties is providedby the mobile phone according to the second embodiment of the invention.

[0034] Although the invention has been described by way of a specificembodiment thereof, it should be apparent that the present inventionprovides a mobile phone with an improved conference call capability thatfully satisfy the aims and advantages set forth above, and alternativesand modifications are possible within the scope of the invention.

[0035] For example, in an alternative embodiment the fixed microphoneand the fixed earphone are replaced by another handsfree device.

[0036] In still another embodiment of the invention, the recordingdevice/devices is/are connected to the phone by a short-range radiocommunication link such as Bluetooth®.

1. A portable communication device for conference calls, comprising atleast first and second speech encoder paths with first and second inputsfor connection to first and second recording devices, respectively, andat least one output connected to signal processor means for receivingand processing first and second electronic signals from said recordingdevices via said first and second speech encoder paths for transmissionto a transmitter/receiver operatively connected to said signal processormeans, wherein said apparatus is adapted to receive said first andsecond electronic signals simultaneously even if the signals aredifferent, and said apparatus comprises a summator adapted to sum saidfirst and second electronic signals into a sum signal for transmissionto said transmitter/receiver.
 2. A portable communication deviceaccording to claim 1, wherein said summator is adapted to sum said firstand second electronic signals into a sum signal for transmission to atleast two outputs, and operatively connected to said signal processormeans, for connection to recording devices, such as earphones.
 3. Aportable communication device according to claim 1, wherein said signalprocessor means is a digital signal processor.
 4. A portablecommunication device according to claim 3, further comprising at leastan analogue-to-digital converter for converting said first and secondelectronic signals into digital signals before input to said digitalsignal processor.
 5. A portable communication device according to claim4, wherein said summator is a part of said digital signal processor. 6.A portable communication device according to claim 4, wherein saidsummator is an analogue summator, which is a part of said first andsecond speech encoder paths for summing said first and second electronicsignal into an analogue sum signal before A/D conversion into a digitalsum signal.
 7. A portable communication device according to claim 2,further comprising a sidetone generator for generating a first sidetoneof said first electronic signal for transmission to said recordingdevices, and a second sidetone of the second electronic signal fortransmission to said recording devices simultaneously via a speechdecoder path of said phone.
 8. A portable communication device accordingto claim 7, wherein said sidetone generator is a part of said digitalsignal processor.
 9. A portable communication device according to claim7, wherein said sidetone generator is an analogue sidetone generatorconnected between said first and second speech encoder paths and saidspeech decoder path of said phone for transmission of said first andsecond electronic signals to first and second earphone outputs of saidspeech decoder path.
 10. A portable communication device according toclaim 1, wherein said first recording device is a conventional fixedmicrophone or a microphone in a first portable handsfree device, andsaid second recording device is a microphone in a second portablehandsfree device, and said first earphone is a conventional fixedearpiece or an earphone in said first portable handsfree device, andsaid second earphone is an earphone in said second portable handsfreedevice.
 11. A portable communication device according to claim 1,wherein at least one of said first and second inputs are adapted forwireless connections to said first and second recording devices.
 12. Aportable communication device according to claim 2, wherein at least oneof said at least two outputs is adapted for wireless connections to atleast two recording devices.
 13. A portable communication deviceaccording to claim 12,wherein said wireless connections are short-rangeradio communication links.
 14. A portable communication device accordingto claim 1,wherein the portable communication device is a mobiletelephone apparatus.
 15. A CODEC block for use in a portablecommunication device for conference calls, comprising first and secondspeech encoder paths, with first and second inputs for connection tofirst and second recording devices, respectively, and a common outputfor connection to signal processor means of a phone, wherein said blockis adapted to receive first and second electronic signals simultaneouslyfrom said recording devices even if the signals are different, and saidblock comprises a summator for summing said first and second electronicsignals into a sum signal for transmission to a transmitter/receiver ofthe phone.
 16. A CODEC block according to claim 15, wherein saidsummator is adapted to sum said first and second electronic signals intoa sum signal for transmission to at least two outputs, and operativelyconnected to said signal processor means for connection to recordingdevices, such as earphones.
 17. A CODEC block according to claim 15,further comprising at least an analogue-to-digital converter forconverting said first and second electronic signals into digital signalsbefore input to said digital signal processor.
 18. A CODEC blockaccording to claim 17, wherein said summator is an analogue summator,which is a part of said first and second speech encoder paths forsumming said first and second electronic signal into an analogue sumsignal before A/D conversion into a digital sum signal.
 19. A CODECblock according to claim 15, further comprising a sidetone generatorconnected between said first and second speech encoder paths and aspeech decoder path for transmission of said first and second electronicsignals to first and second earphone outputs of said speech decoderpath.
 20. A CODEC block according to claim 19, wherein said sidetonegenerator is an analogue sidetone generator.
 21. A method of conferencecalls in a portable communication device, wherein first and secondelectronic signals are received from recording devices operativelyconnected to said portable communication device comprising the steps ofreceiving said first and second electronic signals simultaneously evenif the signals are different, and generating a sum signal of said firstand second electronic signals for transmission to a transmitter/receiverof said portable communication device.
 22. A method according to claim21, further comprising the step of generating a sum signal of said firstand second electronic signals for transmission to at least two outputsof said portable communication device for connection to recordingdevices, such as earphones.
 23. A method according to claim 21, furthercomprising the step of generating a first sidetone of said firstelectronic signal for transmission to said earphone outputs, and asecond sidetone of the second electronic signal for transmission to saidearphone outputs.